Adolescent obesity is a major public health concern and exposure to high levels of food advertising is an important factor. Food commercial exposure has been associated with greater preferences for and consumption of calorie-dense foods. Yet, almost nothing is known about the ways that food marketing impacts adolescents and what factors increase vulnerability to the negative consequences of food advertising. Food marketing may impact adolescents by unconsciously priming desire for food. New preliminary data suggest that adolescents with greater reward-related activation (striatum, amygdala) in response to unhealthy food commercials (relative to non-food commercials and television viewing) show greater increases in Body Mass Index (BMI). Biological, psychological, and environmental factors have been linked with risk for unhealthy weight gain. No prior research has examined how these factors may increase susceptibility to food advertising. Early adolescence is a critical time to understand the impact of food commercials on eating behavior and future BMI, as this age group is a frequent target of food marketing and is at-risk for excess-weight gain. In a sample of 180 adolescents (13-15 years of age), we propose to test the hypothesis that biological- (genotypes associated with high dopamine signaling), psychological- (increased impulsivity, elevated food reinforcement) and environmental- (higher media exposure) factors strengthen the positive association between reward-related neural activation to unhealthy food commercials (relative to healthier food commercials and non-food commercials) and overeating/future increases in BMI. Further, we will identify high- and low-risk phenotypes for obesity by examining how these factors cluster together and predict unhealthy weight gain. This research will increase the success of policy attempts to restrict food advertising to minors by identifying the mechanisms through which marketing impacts adolescents. Further, the proposed research will improve interventions to reduce obesity by identifying which adolescents are most vulnerable to food marketing and what factors may reduce the likelihood of negative outcomes (e.g., reduced media exposure).